A typical production well consists of a wellbore lined with a wellbore casing. The casing is comprised of a string of tubular steel casing joints assembled together. As the casing string is lowered into the wellbore. Additional casing joints are added to the casing string until the wellbore is fully lined.
An imbalance of pressures in the wellbore may cause a blowout as the casing string is lowered into the wellbore. The pressure imbalance may result from a low pressure/high permeability formation in the open wellbore that causes gas to migrate to a column of fluid in the wellbore. If a blowout results, fluid flows toward the surface through the inside of the casing string.
A blowout may be prevented by placing a casing shoe check valve at the bottom of the casing string. However, the casing shoe check valve cannot be used in some applications, such as where the casing string is not hydraulically sealed above the valve. Another method utilizes a packer placed at the bottom, or close to the bottom, of the casing string. The packer includes a check valve and may support a stab-in cementing sleeve. However, this device permanently restricts access to the lower section of the casing and cannot be used where access is needed to place a tool near the bottom of the casing. Additionally, a wellbore may have several branches extending from a central vertical wellbore. In this event, a multi-branch junction is lowered into the wellbore to merge the branches into a single column. However, the casing shoe check valve and packer described above are unsuitable for use with a multi-branch junction.
If the conditions are suitable, the casing string may be lowered into the wellbore without any mechanism to prevent a blowout. However, even in this situation, some localities do not permit a casing string to be lowered into a wellbore without a mechanism in place to prevent a blowout.
It would be advantageous to have a flow control device readily useable with a casing string, especially a casing string having a multi-branch junction. Additionally, it would be advantageous to have a flow control device that could be retrieved quickly, easily, and completely once the casing string is disposed in the wellbore.